PagerTitleStrip under Android v4, page title of ViewPager, androidviewpager

PagerTitleStrip under Android v4, page title of ViewPager, androidviewpager

Android. support. v4.view. PagerTitleStrip

A custom View separated by the Title of the Page. This allows you to flexibly set the title style and text.

Effect:

Xml usage:

<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/pager"android:layout_width="match_parent"android:layout_height="match_parent"><android.support.v4.view.PagerTitleStripandroid:id="@+id/pager_title_strip"android:layout_width="match_parent"android:layout_height="30dp"android:layout_gravity="bottom"android:paddingTop="4dp"android:paddingBottom="4dp" /></android.support.v4.view.ViewPager>

Android: layout_gravity: The title location is generally set to bottom or top.

I can see that this is used in the open-source project ImageLoader. I haven't seen any findbyid for a long time,

It turns out to be a child control of ViewPager in its source code.

Some source code:

 @Override    protected void onAttachedToWindow() {        super.onAttachedToWindow();        final ViewParent parent = getParent();        if (!(parent instanceof ViewPager)) {            throw new IllegalStateException(                    "PagerTitleStrip must be a direct child of a ViewPager.");        }        final ViewPager pager = (ViewPager) parent;        final PagerAdapter adapter = pager.getAdapter();        pager.setInternalPageChangeListener(mPageListener);        pager.setOnAdapterChangeListener(mPageListener);        mPager = pager;        updateAdapter(mWatchingAdapter != null ? mWatchingAdapter.get() : null, adapter);    }

Analysis: When onAttachedToWindow () is used, locate the parent-view directly. If it is ViewPager, an exception is thrown.

Set title Value

In PagerAdapter, there is a getPageTitle (), which needs to be rewritten, and different titles can be returned based on different pages.

@Overridepublic CharSequence getPageTitle(int position) {switch (position) {case 0:return getString(R.string.title_list);case 1:return getString(R.string.title_grid);default:return null;}}

In the updateText () source code of PageTitleStrip, the adapter. getPageTitle of viewPager is called, and the title is obtained and set.